Supersensitization of photographic silver halide emulsions



United States Patent O SUPERSENSITIZATION OF PHOTOGRAPHIC SLVER HALIDE EMULSIONS Burt H. Carroll and Jean E. Jones, Rochester, N. Y., as-

signors to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey Application `lanuary 13, 1954, Serial No. 403,822

17 Claims. (Cl. 95-7) This invention relates to photographic emulsions containing cyanine dyes, and in supersensitizing combination, certain un-ionized dyes.

It is known in the art of making photographic emulsions that certain dyes of the cyanine class alter the sensitivity of photographic emulsions of the gelatine-silverhalide kind, when the dyes are incorporated in the emulsions. It is also known that the sensitization produced by a given dye varies somewhat with the type of emulsion in which the dye is incorporated. Furthermore, the sensitization of a given emulsion by a given dye may be altered by varying the conditions in the emulsion. For example, the sensitization may be increased by increasing the silver ion concentration or decreasing the hydrogen ion concentration (i. e. increasing the alkalinity) or both. Thus, sensitization can be increased by bathing plates, coated with a spectrally sensitized emulsion, in water or in aqueous solutions of ammonia. Such a process of altering the sensitivity of a sensitized emulsion by increasing the silver ion concentration and/ or by decreasing the hydrogen ion concentration is commonly called hypersensitization. Hypersensitized emulsions have generally poor keeping qualities.

We have now found a new means of altering the sensitivity in emulsions containing cyanine dyes. Since the conditions in the emulsion, i. e. the hydrogen ion and/or the silver ion concentration undergo little or no change in our method, we shall designate our new method as a kind of supersensitization.

It is, therefore, an object of our invention to provide photographic emulsions containing cyanine dyes, and in supersensitizing combination therewith, certain un-ionized dyes. Another object is to provide a process for preparing these supersensitized emulsions. Other objects will become apparent from a consideration of the following description and examples.

The cyanine dyes useful in practicing our invention can advantageously be represented by the following general formula:

2,704,714 Patented Mar. 22, 1955 cyclic nucleus of the naphthothiazole series (e. g. a-naphthothiazole, -naphthothiazole, 7-methoXy-a-naphthothiazole, 8-methoxy-a-naphthothiazole, 5-methoxynaphthothiazole, 5-ethoXy-a-naphthothiazole, etc.), a heterocyclic nucleus of the benzoselenazole series (e. g. benzoselenazole, S-chlorobenzoselenazole, 6-methoxybenzoselenazole, S-methoxybenzoselenazole, etc.), a heterocyclic nucleus of the naphthoselenazole series (e, g. zt-naphthoselenazole, 15J-naphthoselenazole, etc.), a heterocyclic nucleus of the benzoxazole series (e. g. benzoxazole, S-hydroxybenzoxazole, -hydroxybenzoxazole, 5-chlorobenzoxazole, S-methoxybenzoxazole, -methoxybenzoxazole, 5-phenylbenzoxazole, 5-bromobenzoxazole, etc), a heterocyclic nucleus of the naphthoxazole series (e. g. a-naphthoxazole, -naphthoxazole, etc.), a heterocyclic nucleus of the 2-quinoline series (e. g. 2-quinoline, 6- methyl 2 quinoline, 7 methyl 2 quinoline, 8- methyl-Z-quinoline. 6-chloro-2-quinoline, S-chloro-Z-quinoline, 4-chloro-2-quinoline, 5-ethoXy-2-quinoline, 6-ethoxy-2-quinoline, 7-ethoXy-2-quinoline, 6-hydroXy-2-quinoline, 7hydroXy-2-quinoline, 6 methoxy 2 quinoline, etc.), a heterocyclic nucleus of the 4-quinoline series (e. g. 4-quinoline, 6-methoXy-4-quinoline, 7-methyl-4- quinoline, 8-methyl-4-quinoline, etc.), etc. However, cyanine (i. e. simple cyanine and carbocyanine) dyes wherein both Z and Z1 represent the non-metallic atoms necessary to complete a heterocyclic nucleus of the quinoline series and R2 and/ or Rs represent an alkyl group are not advantageous in practicing our invention.

The un-ionized dyes useful in practicing our invention can advantageously be represented by the following general formula:

II S

wherein R4 and R5 each represents an alkyl group, i. e. an alcohol radical, e. g. methyl, ethyl, n-propyl, n-butyl, -hydroxyethyl, carbethoxymethyl, benzyl (phenylmethyl), etc., Q representsthe non-metallic atoms necessary to complete an indandione nucleus or a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, such as those of the pyrazolone series (e. g. 3-methyl-l-phenyl-S-pyrazolone, l-phenyl-S-pyrazolone, 1-(2 benzothiazolyl-3-methyl-S-pyrazolone, etc.), those of the isoxazole series (e. g. 3phenyl-5(4H)isoxazolone, 3- methy1-5-(4H)isoxazolone, etc.), those of the indandione series (e g. 1,3-diketohydrindene, etc.), those of the oxinwherein R and R1 each represents an alkyl group, such as methyl, ethyl, n-propyl, carbethoxymethyl, etc., R2 and R3 each represents a hydrogen atom or an alkyl group, such as methyl, ethyl, n-propyl, etc., d, m, and n each represents a positive integer of from l to 2, X represents an acid radical, such as chloride, iodide, bromide, perchlorate, p-toluenesulfonate, benzenesulfonate, ethylsulfate, methylsulfate, etc., and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, e. g. a heterocyclic nucleus of the thiazole series (e. g. thiazole, 4-methylthiazole, 4-phenylthiazole, S-methylthiazole, S-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazole, etc.), a heterocyclic nucleus of the benzothiazole series (e. g. benzothiazole, 4chlorobenzo thiazole, 5-chlorobenzothiazole, -chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole, S-methylbenzothiazole, -methyl'oenzothiazole, S-bromobenzothiazole, -bromobenzothiazole, 4phenylbenzothiazole, 5- phenylbenzothiazole, 4-methoxybenzothiazol, 5-methoXybenzothiazole, 6-methoxybenzothiazole, 6-iodobenzothiazole, 5-iodobenzothiazole, 4-ethoxybenzothiazole, 5-ethoxybenzothiazole, 5,6-dimethoxybenzothiazole, S-hydroxybenzothiazole, -hydroxybenzothiazole, etc.), a heterodole series (e. g. lalkyl-2,3-dihydro-Z-oxindoles, etc.), those of the 2,4,-triketohexahydropyrimidine series (e. g. barbituric acid or 2-thiobarbituric acid as well as their lalkyl (e. g. l-methyl, 1ethyl, l-n-propyl, l-n-heyptyl, etc.), or 1,3-dialkyl (e. g. 1,3-dimethyl, 1,3-diethyl, 1,3-di-npropyl, 1,3-diisopropyl, 1,3-dicyclohexyl, l,3-di(meth Oxy-ethyl), etc.), or 1,3-diaryl (e. g. 1,3-diphenyl, 1,3-di(p chlorophenyl), 1,3-di(p-ethoxycarbonylphenyl), etc.), or 1-aryl (e. g. l-phenyl, l-p-chlorophenyl, l-p-ethoxycarbonylphenyl), etc.) or 1alkyl3aryl (e. g. l-ethyl-3-phenyl, 1-n-heptyl-3-phenyl, etc.) derivatives, those of the rhodanine series (i. e. 2-thio-2,4thiazolidinedione series) such as rhodanine, 3alkylrhodanines (e. g. B-ethylrhodanine, 3-allylrhodanine, etc.) or 3-arylrhodanines (e. g. 3-phenylrhodanine, etc.), etc., those of the 2(3H)imidazo 1,2- a pyridone series, those of the 5,7dioxo-6,7dihydro5 thiazole[3,2a]pyrimidine series (e. g. 5,7-dioXo-3-phenyl- 6,7-dihydro-5-thiazolo[3,2-alpyrimidine, etc), those of the 2-thio-2,4oxazolidinedione series (i. e. those of the 2-thi0-2,4(3H,5H)-oxazoledione series) (e. g. 3-ethyl-2- thio2,4oxazolidinedione etc.), those of the thianaphthenone series (e. g. 2(3H)thianaphthenone, etc.), those of the 2-thio-2,5thiazolidinedione series (i. e. the 2-thio- 2,5(3H,5H)thiazoledione series) (e. g. 3-ethy1-2-thio- 2,5-thiazolidinedione, etc.), and Z2 represents the nonmetallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocychc ring, e. g. a heterocyclic nucleus of the benzothiazole series (e. g. benzothiazole, 4-chlorobenzothiazole, 5chlo robenzothiazole, 6-chlorobenzothiazole, 7-chlorobenzothiazole, 4-methylbenzothiazole, S-methylbenzothiazole, 6-methylbenzothiazole, 5-brornobenzothiazole, 6-bromobenzothiazole, 4-phenylbenzothiazole, 5-pheny1benzothiazole, 4-methoxybenzothiazole, S-methoxybenzothiazole, 6-methoxybenzothiazole, -iodobenzothiazole, 5-iodoben- Vzothiazole, 4-eth0xybenzothiazole, 5-ethoxybenzothiazole,

5,6-dimethoxybenzothiazole, S-hydroxybenzothiazole, 6-

hydroxybenzothiazole, 7-hydroxybenzothiazole, etc.), a

wherein R, R1, R2, n, m, X, Z and Z1 each have the values given above.

Symmetrical carbocyanine dyes embraced by Formula I above which have been found to be particularly useful comprise those dyes represented by the following general formula:

wherein R, R1, R3, X, m, n, and Z each have the values given above. When R3 represents an alkyl group, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus other than a heterocyclic nucleus of the quinoline series.

Unsymmetrical carbocyanine dyes embraced by Formula I above which have been found to be particularly useful comprise those dyes represented by the following general formula:

wherein R, R1, R3, X, n, and Z and Z1 each have the values given above (provided, of course, that Z and Z1 are different from one another).

The dyes represented by Formulas I, III, IV, and V above have been previously described in the prior art. See, for example, U. S. Patents 1,861,836 (dated June 7, 1932), 1,934,657 (dated November 7, 1933), 1,935,696 (dated November 21, 1933), 1,950,876 (dated March 13, 1934), 1,990,681 (February 12, 1935), and 2,112,140 (dated March 22, 1938), and Br. 439,857.

The dyes of Formula II are described in the copending application Serial No. 282,696, iiled April 16, 1952 (now abandoned), and Serial No. 375,279, led August 19, 1953, of Leslie G. S. Brooker and F. L. White.

According to our invention, we incorporate one or more of the cyanine dyes selected from those represented by Formulas I, III, IV, or V above with one or more of the dyes selected from those represented by Formula Habove in a photographic emulsion. Our invention is particularly directed to the ordinarily employed gelatino-silverhalide emulsions. However, our supersensitizing combinations can be employed in silver halide emulsions in which the carrier is other than gelatin, e. g., a resinous substance or cellulosic material which has no deteriorating effect on the light-sensitive materials.. l

The sensitizing dyes can be employed in various concentrations depending upon the effects desired. As is well known in the art, the sensitivity conferred upon an emulsion by a sensitizing dye does not increase proportionately to the concentration of the dye in the emulsion, but rather passes through a maximum as the concentration is increased. In practicing our invention, the individual sensitizing dyes are advantageously employed in a concentration somewhat less than their optimum concentration (i. e. the concentration at which the individual dyes give greatest sensitivity). If each of the dyes in the supersensitizing combination is employed' in its optimum concentration, it is possible, in certain cases that the sensitization produced by the supersensitizing combination will have passed through a maximum.

The optimum concentration of an individual sensitizing dye can be determined in a manner well known to those skilled in the art by measuring the sensitivity of a series of test portions of the same emulsion, each portion containing a different concentration of the sensitizing dye. The optimum concentration of our supersensitizing combinations can, of course, be readily determined in the same manner, by measuring the sensitivity of a series of test portions of the same emulsion, each portion containing different concentrations of the individual dyes in the combination. In determining the optimum concentration for the supersensitizing combination, it is advantageous to employ, at first, concentrations of the individual dyes less than their optimum concentrations. The concentrations of the individual dyes can then be increased until the optimum concentration of the supersensitizing combination is determined.

Ordinarily the optimum or near optimum concentration of the cyanine (i. e. simple cyanine and carbocyanine) dyes selected from those represented by Formula I (or Formulas III, IV, or V) above, which we employ in practicing our invention, is of the order of from 0.05 to 0.3 g. per mol. of silver halide in the emulsion.

The un-ionized dyes selected from those represented by Formula Il above are advantageously employed in concentrations on the order of from 0.05 to 0.3 g. per mol. of silver halide in the emulsion.

Generally speaking, the ratio of concentration of the dye of Formula II to the cyanine dye of Formula I (or III, IV, or V) can vary rather widely in our combinations, e. g. from 1:20 to 3:1 by weight in many cases.

The methods of incorporating sensitizing dyes in emulsions are well known to those skilled in the art. ln practicing our invention, the sensitizing dyes can be incorporated in the emulsions separately or together. It is convenient to add the dyes separately in the form of solunl I tions in appropriate solvents. Methanol, ethanol, pyridine, etc. (and especially pyridine) have proven satisfactory as solvents for the dyes of Formulas I, II, III, IV, and V which we employ. Acetone has also been found to be a suitable solvent in certain cases. Pyridine has been found to be a particularly eflicacious solvent, in that an enhanced supersensitizing effect is demonstrated in certain cases when pyridine is employed. It has also been noted that while certain of the dyes of Formula Il have only a slight sensitizing action (or no detectable action) when used alone, when the dyes of Formula II are used in conjunction with pyridine a noticeable increase in speed is observed. Pyridine is not essential to successful operations according to our invention, however. In general, it is advantageous to employ pyridine, diluted with methanol or acetone, as the solvent for the supersensitizing combinations of our invention. For example, the dye can be dissolved in pyridine and the solution then diluted with methanol or acetone. The dyes are advantageously incorporated in the nished, washed emulsions and should be uniformly distributed throughout the emulsions. The following procedure is satisfactory: Stock solutions of the sensitizing dyes desired are prepared by dissolving the dyes in appropriate solvents as described above. Then, to the owable gelatino-silver-halide emulsion, the desired amounts of the stock solution of one of the dyes are slowly added, while stirring the emulsion.

Stirring is continued until the dye is thoroughly incorporated in the emulsion. Then the desired amount of the stock solution of the second dye is slowly added to the emulsion, while stirring. Stirring is continued until the second dye is thoroughly incorporated. The supersensitized emulsion can then be coated out on a suitable support, such as glass, cellulose derivative lm, resin lrn, or paper, to a suitable thickness and allowed to dry. 'I'he details of such coating methods are well known to those skilled in the art.

The amounts of the individual sensitizing dyes actually incorporated in the emulsion will vary somewhat from dye to dye, according to the emulsion employed and according to the effect desired. The regulation and adoption of the most economical and useful proportions will be apparent to those skilled in the art upon making the ordinary observations and tests customarily employed in the art. Accordingly, the foregoing procedures and proportions are to be regarded only as illustrattive. Clearly our invention is directed to any emulsion containing a combination of the aforesaid sensitizing dyes whereby a supersensitizing effect is obtained.

The following examples will serve to illustrate further the manner of practicing our invention. To different portions of the same batch of photographic gelatinosilver-bromiodide emulsion were added (l) a cyanine dye selected from those of Formula I (or III, IV, or V) above and (2) a combination of the cyanine dye of Formula I (or III, IV, or V) and an un-ionized dye selected from those represented by Formula II above. In some instances, a third coating was prepared using the same emulsion formula and adding only one of the un-ionized dyes selected from those of Formula II. In some instances, the table will show that this third coating gave only a low speed or one too low to measure in the the table).

Different emulsions were used in some of the examples, although the emulsions of each individual example were obtained from the same batch. However, the coatings of Examples l and 2 were obtained from the same batch of emulsion. The coatings of Examples 3, 6, and 7 were obtained from the same batch of emulsion, the coatings of Examples 4, 5, 9, 10, 11, and l2 were obtained from the same batch of emulsion, the coatings of Examples 13 to 17, 52, and 53 were obtained from the same batch of emulsion, the coatings of Examples 18 to 21 were obtained from the same batch of emulsion, the coatings of Examples 22 to 29, 54, 55, and 56 were obtained from the same batch of emulsion, the coatings of Examples 30 and 31 were obtained from the same batch of emulsion, and the coatings of Examples 32 to 51 were obtained from the same batch of emulsion. The coatings of Examples 1 to 12, 30 and 31 contained 20 cc./mol. AgX of pyridine, while the coatings of Examples 18, 19, 20 and 21 contained 30 cc./mol. AgX of pyridine. Before coating, the emulsions containing the sensitizing dyes were digested for a short time in a tank maintained at 52 C. The different portions of emulsion were then coated on supports and exposed in the usual manner in a spectrograph and a sensitometer (Type Ib) through a Wratten 25 filter, i. e., a filter which transmits substantially no light of wavelength shorter than 5 80 mit, and the exposed emulsions developed in the usual manner. The speed (red) gamma and fog for each of the coatings was determined and the results are recorded in Table A below. Further examples are recorded in Table B below, wherein additional information is given in certain instances with respect to a green light exposure, the exposure being made through a Wratten 58 filter, i. e. a filter which transmits only light of Wavelengths lying between 465 arid 620 mn. The results folregion transmitted by the lter (designated asterisk 1n 3 low:

Table A Red Light Exposure Ex. Dye (glmol. AgX) 10/1 Speed Gamma Fog (a) 9-Ethyl-I,3-dimethylthia-2earbocyaniue iodide (0.080) 8. 2 1. 97 05 1 (b) 1,3Dei-[di(1-ethy1-2(1H)--naphtliotliiazolyliderie)isopropylideiie] barbituric 9.0 1. 72 05 aci (c) dye (a) (0.080) plus dye (b) (0.020) 35.0 2. 23 04 2 (d) 9-Ethyl1',3dimethyl4,-benzoselena2'carbocyani.ue iodide (0080).... 3. 2 0. 76 04 (e) dye (d) (0.080) plus dye (b) (0.020)... 12.0 2.30 .04 (f) 9-Etliyl3,3dimethyl4,5,4,5dibenzothiacarbocyauiue chloride (0.080) 24. 5 2.97 05 3 (g) dye (b) (0.020) 7.1 1.76 .05 (h) dye (f) (0.080) plus dye (b) (0.020).-- 48.0 2. 56 .06 4 9-Ethyl-3,3dimethy1thiacarboeyanine bromide (0.080) 4. 9 2. 47 05 (j) dye (i) (0.080) plus dye (b) (0.020)---.. 26.5 3.2 .05 (k) 2Ethy13,3dimethy14,5,4',5dibenzoselenacarbocyanine iodide (0.080)-. 8. 0 2. 32 05 5 (l) dye (b) (0.020) 7.3 1. 03 05 (m) dye (k) (0.080) plus dye (b) (0.020) 10. S 2. 80 .05 (n) dye j) 0.080 24. 5 2. 97 .05 6 (o) 13)t l)i2yl5[ d i(1 ethyl-2(1H)B naphthothiazolylidene) isopropylidene] barbituric acid 05 (p) dye (f) (0.080) plus dye (o) (0.020) 42. 2. 68 06 (q) [(3 Ethyl-2(3H)a naphthothiazolylidene) (1 ethyl-2(1H)--riaphthothiazolylidene) 6. 6 2. 68 05 7 isopropylidene]-1-methyl-2-thiobarbitufic acid (0.020).

(r) dye (f) (0.080) plus dye (q) (0.020) 31.0 2. 92 06 (s) 2-[Di-(1ethyl-2(1H)--naphthotliiazolylidene)isopropylidene]-1,3-indandi0ne (0080).-.. 3.0 1. 84 06 s (t) dye (f) (0.080) 21.0 2. 52 .o6 (u) dye (0.080) plus dye (s) (0.040) 37.0 2.50 06 (v) 4-[1Di-(eioyl-LOly-naphthothiazolylidene) isopropylidene13phenyl-5(4H)1soxazo 6. 8 3. 4 04 ODG 9 (w) dye (i) (0.080) 4. 9 2. 47 .05 (z) dye (i) (0.080) plus dye (u) (0.020) 21.0 2. 90 .04 10 {(Zl) dye (9) (01140) .05 (z) dye (c) (0.080) plus dye (o) (0.020) 24. 5 3.28 04 n {(a) dye (k) (0.080 8.0 2. 32 .05 (b') dye (k) (0.080) pius dye (u) (0.020)--- 14-5 289 -05 12 (c') dye (k) (0.080) plus dye (o) (0.020) 11.5 2.27 .05 (d') 3,3Diethy1thiacarbocyan1ne iodide (0.080) 6. 1 1. 90 05 13 (e) 5-[1-Ethy1-2(1H)Bnaplithothiazolylidene) (1-methyl-2(1H)-B-riaphthothiazolylidene) 5. 2 2. 77 06 isopropylidene]1,3di(-methoxyethyl)barbituric acid (0.080). (f) dye (d) (0.080) plus dye (e) (0.080)- 48.0 1.62 .08 14 {(g) 3,3'-Diethyl4,4'dimethylthiazolocarbocyanme iodide (0.080) 5.0 2.60 .04 (h') dye (g) (0.080) plus dye (e) (0.080)-. 35. 5 2. 12 06 15 3,3Diethy1oxathiacarhocyanme iodide (0.080) 2. 5 1. 30 04 (j) dye (0.080) plus dye (e) (0.080) 44.0 1.70 .06 15 (k) 3,3Diethyl4,5,4',5dibenz0thiacarbocyaume bromide (0.080) 14. 0 2. 48 06 (Z') dye (k) (0.080) plus dye (e) (0.080). 26. 5 2.26 .08 17 {(m') 3,3Diethy1-4,5,4,5dibenzoselenacarbocyanine iodide (0.080) 13.5 2.03 05 (n) dye (n) (0.080) plus dye (e) (0.080) 17. 5 2.38 .07 18 (o) dye 0.08 34. 0 1. 06 .06 (p') 5-[(1Ethyl2(1H) -naphthothlazolylidene) (1 methyl-2(1H) --naphtlioselenazolyli- 29. 0 2. 34 06 dene) isopropylidene]-1,3di (B-methoxyethyl) barbituric acid (0.080) (q') dye (f) (0.080) plus dye (p') (0.025) 52.0 0.82 .07 19 {(r') 5-[(D i(1etlgl2(1H)--naphthothlazolylidene) isopropylidenel111- heptylbarbituric 8. 2 0. 70 06 aci 0.0 (3') dye (f) (0.080) plus dye (r) (0.025) 62. 0 0. 93 07 20 {(t) dye (i) (0.080) 7.1 1.6 .05 (u) dye (i) (0.080) plus dye (p') (0.025) 35.6 2.44 .06

Table A Continued Red Light Exposure Ex. Dye (gJmol. AgX) 10/1 Speed Gamma Fog dye (i) (0.080) plus dye (r) (0.025) 26. 5 2. 1 06 dye (i) 0.08 17.0 1.30 .05 5-[(1 Ethy1-2(1H)-naphthothiazolylidene) (3-methylv2(3H)a1iaphthoxazolylidene) 6.8 2. 72 05 isopropylidene]1,3di(B-methoxyethyl) barbiturie acid (0.080). dye (i) (0.080) plus dye (z) (0.030) 33.0 1. 76 .06 5-[(1 Etbyl2(1H)- naphthotbiazolylidene) (1- methyl-2(1H)Bnaphtlioxazolylidene) 23. 0 1. 87 05 isopropylidene]1,3di(1S-methoxyethyDbarbitui-i r acid (0.080) dye (i) (0.080) plus dye (2') (0.080). 66. 0 1.0 06 5[(1 Etbyl-2(1H) naphthothiazolylidene) (3-inethyl2(3H)-anaphthothiezolylidene 12. 6 2. 70 05 isopropylidene]1,3-di(-methoxyethyDbarbiturie acid (0.080). dye (i) (0.080) plus dye (b) (0.080) 24.0 1.7 .05 5,5-Dich]oro-3,3triethylthiacarboeyenine bromide (0.080). 39.0 1. 64 06 dye (d) (0.080) plus dye (I) (0.030) 41. 0 1. 72 06 dye (11") (0.080) plus dye (z) (0.030) 62.0 1. 51 .07 dye (d) (0.080) plus dye (6) (0030)..-. 50.0 1. 40 07 dye (e) (0.080) 4. 4 2. 34 0. 5 dye (e) (0.030) plus dye (d) (0.080). 80.0 1. 43 .07 1,1Diethyl-2,2earbocyanine iodide 11.8 1.34 .05 dye (e') (0.080) plus dye (j) (0.040) 25.0 2. 47 .07

Table B Red Light Green Light Exposure Exposure Ex. Dye (g./mol. AgX) Fog 10/i 10/1l Speed Gamma Speed Gamma 1,1'Diethyl2,2eyanine iodide (0.040) 2. 8 1. 06 04 dye (b) (0040)-- 9.0 1. 72 4. 5 1. 42 .05 dye (1") (0.040) plus dye (b) (0.040)- 8 6 2.16 12.6 2. 06 .o5 3,3Diethyl4,5,4,5dibenzothiacyaniiie iodide (0.040). 3. 8 0. 92 04 dye (0") (0.040) plus dye (b) (0.040) 19. 0 2. 56 3. 9 1. 26 .04 dye (e) (0.080) 4.7 2.36 .05 3,3'Diethylselenacyanine iodide (0.080).. 04 dye (e') (0.080) plus dye (r") (0.080) 33.0 1. 52 06 dye (p) (0080)---- 3.9 2.32 .05 dye (r") (0. 80) plus dye (11') (0.080) 37.0 1.25 .05 dye (b) (0.080) .06 dye (b) (0.080) plus dye'(r") (0.080)-.. 3. 55 0.44 .05 3,3Diethy1oxaeyanine iodide (0.080).- 03 dye (2") (0.080) plus dye (e) (0.080)... 29. 0 1. 49 .05 dye (p') (0.080) plus dye (1) (0.080) 31.0 1.10 .05 dye (a:") (0.080) plus dye (b) (0.080). 11.2 0.52 .05 33Diethy14,5,4',5'dibei1zoxacyanine iodide (0.080) .03 dye (b") (0.080) plus dye (e') (0.080) 4. 2 1.4 .05 dye (b") (0.080) plus dye (p') (0.080) 4. 3 1. 6 05 dye (0") (0.0 5. 3 1. 2 .04 dye (0") (0.080) plus dye (e) (0.080) 36. 0 1. 78 5.0 1. 52 .07 dye (0) (0.080) plus dye (p') (0.080) 38.0 1. 78 5. 5 1. 32 .05 dye (0) (0.080) plus dye (b) (0.080) 17.8 2.04 4. 5 1.72 .05 dye (l") (0.080) 4.4 1.68 .04 dye (1) (0.080) plus dye (e) (0.080). 46.0 1. 92 25. 5 1. 78 .06 dye (1") (0.080) plus dye (p) (0.080) 39.0 1. 90 24. 5 1. 78 .05 dye (1") (0.080) plus dye (b) (0.080) 9.40 1.42 31.0 1.37 .06 1'-Ethyl2-metbylthia2cyanine iodide (0.080) 18. 0 1. 73 04 dye (mm) (0.080) plus dye (e') (0.080) 56.0 1. 62 20. 5 1. 41 05 dye (mm) (0.080) plus dye (p) (0.080). 58. 0 1. 44 22. 5 1. 16 05 dye (mm) (0.080) plus dye (b) (0.080) 6.9 1.92 24.0 1.8 .06 1,3-DiehyI-6methoxy5pheiiylthia-2eyanine p-t 29. 0 1. 72 04 dye (41 (0.080) plus dye (e) (0.080) 24.0 2. 0 14. 8 1. 59 06 dye (q) (0.080) plus dye (b) (0.080). 4. 7 1. 72 17. 8 1. 94 .06 dye (q") (0.080) plus dye (p') (0.080) 22. 5 2.08 13.0 1. 72 .05 3,3,8trii:nethy1thiaeyanine perchlorate (0.080). 04 dye (um) (0.080) plus dye (e) (0.080) 53.0 1. 73 06 1,3,8trimethy1thia2'eyanine perchlorate (0.080) 04 dye (w) (0.080) plus dye (e) (0.080) 34.0 2.0 .06 dye (1") (0.080) 3. 8 1. 15 09 dye (1) (0.080) plus dye (rr) (0.080) 35. 0 1. 85 14. 0 2.20 05 dye (1) (0.080) plus dye (2') (0.080) 38. 0 1. 71 25. 0 1. 66 05 dye (l) (0.080) plus dye (b) (0.080) 15.0 1. 93 9.0 2.32 .06

Dye (b") which was used in- Examples 38 and 39 caused 0.3 log E desensitization in the emulsion, which accounts for the apparent lower red speed. The red/ blue ratio for these coatings is higher, however, than for the coatings not supersensitized.

The accompanying drawing illustrates the supersensitizing effect obtained with three of our new combinations of dyes in gelatino-silver-bromiodide emulsions. Each figure of the drawing is a diagrammatic reproduction of three, or in the case of Figure 3, two, spectrograms. In each ligure the sensitivity of the emulsion containing the cyanine dye of Formula I (or 11i), 1V, or V) is represented by the solid curve. T he uppermost curve (broken line) represents the sensitivity conferred on the emulsion by the combination of the cyanine dye of Formula I (or III, IV, 0r V) and the un-ionized dye of Formula II. In Figures 1 and 2 the third curve (also broken line) represents the sensitivity conferred on the emulsion by the un-ionized dye of Formula II alone. This third curve has been omitted in Figure 3 inasmuch as it would be identical to curve E in Figure 2.

ln Figure 1, curve A represents the sensitivity of an ordinary gelatino-silver-bromiodide emulsion sensitized with 9 ethyl 3,3'-dimethyl-4,5,4,5'-dibenzothiacaroocyanine chloride, curve B represents the sensitivity of the same emulsion containing 2-[di-(1-ethy1-2(1H)naph tho-thiazolylidene) isopropylidene]-1,3indandione, and curve C represents the sensitivity of the same emulsion containing both 9-ethy13,3dimethyl4, 5,4',5dibenzothacarbocyanne chloride and 2-[di-(1-ethy1-2(1H) naphthothiazolylidene) isopropylidene]-1,3-indandione. The sensitometric measurements for these emulsions are given in Example 8 of Table A.

In Figure 2, curve D represents the sensitivity of an ordinary gelatino-silver-bromiodide emulsion sensitized with 9-ethyl-1',3diniethylthia-2carbocyanine iodide, curve E represents the sensitivity of the same emulsion containing 1,3-diethy1-5- [di-( l-ethyl-Z( 1H) --naphthothiazolylidene) isopropylidenel barbituric acid, and curve F represents the sensitivity of the same emulsion containing both 1,3-diethyl5-[di(1-ethyl-2(1H)naph thothiazolylidene] isopropylidene) barbituric acid and 9- ethyl- 1',3 dimethylthia 2' carbocyanine iodide. The 5 sensitometric measurements for these emulsions are given in Example l of Table A.

In Figure 3, curve G represents the sensitivity of an ordinary gelatino-silver-bromiodide emulsion sensitized with 3,3'-diethyl4, 5,45'dibenzothiacyanine iodide and curve H represents the sensitivity of the same emulsion containing both 3,3-diethyl-4,5,4,5-dibenzothiacyanine iodide and 1,3-diethyl-5-[di-(1-ethyl-2( 1H) --naphthothiazolylidene) isopropylidene] barbituric acid. The sensitometric measurements for these emulsions are given in Example 31 of Table B.

Our invention is primarily directed to the ordinarily employed gelatino-silver-halide developing-out emulsions, e. g. gelatino-silver-chloride, -chlorobromide, -chloroiodide, -chlorobromiodide, -bromide and -brorniodide de- Veloping-out emulsions. While the results in the above tables were obtained using gelatino-silver-bromiodide emulsions, excellent results have also been obtained using gelatino-silver-chlorobromide emulsions. Emulsions which form the latent image mostly inside the silver halide grains, such as the emulsions set forth in U. S. Patent 2,456,956, dated December 2l, 1948, can also be employed in practicing our invention.

The emulsions prepared in accordance with our invention can be coated in the usual manner on any suitable support, e. g. glass, cellulose nitrate film, cellulose acetate lm, polyyinylacetal resin film, paper or metal.

Photographic silver halide emulsions, such as those listed above, containing the supersensitizing combinations of our invention can also contain such addenda as 30 chemical sensitizers, e. g. sulfur sensitizers (e. g. allyl thiocarbarnide, thiourea, allylisothiocyanate, cystine, etc.), various gold compounds (e. g. potassium chloroaurate, auric trichloride, etc.) (see U. S. Patents 2,540,- 085, 2,597,856 and 2,597,915), various palladium com- 40 pounds, such as palladium chloride (U. S. 2,540,086), potassium chloropalladate (U. S. 2,598,079), etc., or mixtures of such sensitizers; antifoggants, such as ammonium chloroplatinate (U. S. 2,566,245), ammonium chloroplatinite (U. S. 2,566,263), benzotriazole, nitrobenzimidazole, 5-nitroindazole, benzidine, mercaptans, etc. (see Mees-The Theory of the Photographic Process, Macmillan Pub., page 460), or mixtures thereof; hardeners, such as formaldehyde (U. S. 1,763,533), chrome alum (U. S. 1,763,533), glyoxal (U. S. l,870,- 354), dibromacrolein (Br. 406,750), etc.; color couplers, such as those described in U. S. Patent 2,423,730, Spense and Carroll U. S. application Ser. No. 771,380, filed August 29, 1947, now Patent No. 2,640,776 etc.; or mixtures of such addenda. Dispersing agents for 5' color couplers, such as those set forth in U. S. Patents 2,322,027 and 2,304,940, can also be employed in the above-described emulsions.

In the above table it will be noted that in certain examples the amounts of dyes used in the supersensitizing combinations do not correspond to the amounts used with each dye alone. Actually, supersensitization occurs according to our invention when the combination of dyes gives more speed than either dye alone at any concentration. Thus, in some instances, the amount of dye, .5 when used alone, is not identical with that used in the supersensitizing combination. This is due to the fact that optimum conditions have been used, insofar as possible, in each of the coatings. Use of larger amounts of dyes in the supersensitizing combinations is not necessary, and in some instances, is actually detrimental.

What we claim as our invention and desire secured by Letters Patent of the United States is:

l. A photographic silver halide emulsion sensitized with a supersensitizing combination of at least one cyanine dye selected from those represented by the following general formula:

` 10 represents an acid radical, d, m, and n each represents a positive integer of from l to 2, and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, provided that when the intercyclic chain contains an alkyl substituent only one of the groups selected from the group consisting of Z and Z1 can represent the non-metallic atoms necessary to complete a heterocyclic nucleus of the quinoline series, and at least one un-ionized dye selected from those represented by the following general formula:

wherein R4 and R5 each represents an alkyl group, Q represents the non-metallic atoms necessary to complete a nucleus selected from the group consisting of those of the indanione series, those of the barbituric acid series, those of the 2-thiobarbituric acid series, andthose of the isoxazolone series, and Z2 represents the nonmetallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the naphthoselenazole series, and those of the naphthoxazole serles.

2. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of at least one cyanine dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group containing from 1 to 2 carbon atoms, R3 represents a member selected from the group consisting of a hydrogen atom and an alkyl group containing from l to 2 carbon atoms, X represents an acid radical, n represents a positive integer of from 1 to 2, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the naphthoselenazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the Z-quinoline series, and those of the 4-quinoline series, and Z1 represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazoleseries, those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the naphthoselenazole series, those of the benzoxazole series, and those of the naphthoxazole series, and at least one unionized dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group, R2 and R3 each represents a member selected from the group consisting of a hydrogen atom and an alkyl group, X 55 the indandione series, Vand those of the isoxazolone series, and Z2 represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the naphthothiazole series, those of the naphthoselenazole series, and those of the naphthoxazole series.

3. A photographic gelatino-silver-bromiodide emulsion sensitized with a supersensitizing combination of at least one cyanine dye selected from those represented by the following general formula:

wherein R and AR1 each represents an alkyl group containing from 1 to 2 carbon atoms, R3 represents a member selected from the group consisting of a hydrogen atom and an alkyl group containing from 1 to 2 carbon atoms, X represents an acid radical, n represents a positive integer of from 1 to 2, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the naphthoselenazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the 2-quinoline series and those of the 4-quinoline series, and Z1 repre- 12 benzoselenazole series, those of the naphthoselenazole series, those of the benzoxazole series, and those of the naphthoxazole series, and at least one un-ionized dye electeld from those represented by the following general ormu a:

sents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the naphthoselenazole series, those of the benzoxazole series, and those of the naphthoxazole series, and at least one un-ionized dye selected from those represented by the following general formula:

wherein R4 and R5 each represents an alkyl group containing from 1 to 2 carbon atoms, Q represents the nonmetallic atoms necessary to complete a heterocyclic nucleus of the barbituric acid series, and Z2 represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series.

4. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of at least one cyanine dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group containing from 1 to 2 carbon atoms, R3 represents a member selected from the group consisting of a hydrogen atom and an alkyl group containing from 1 to 2 carbon atoms, X represents an acid radical, n represents a positive integer of from 1 to 2, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from wherein R and R1 each represents an alkyl group containing from l to 2 carbon atoms, d, m and n each represents a positive integer of from 1 to 2, X represents an acid radical, and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the naphthoselcnazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the 2-quinoline series, and those of the 4-quinoline series, and at least one nn-ionized dye selected from those represented by the following general formula:

wherein R4 and R5 each represents an alkyl group containing from 1 to 2 carbon atoms, Q represents the nonmetallic atoms necessary to complete a nucleus selected from the group consisting of those of the barbituric acid series, those of the Z-thiobarbituric acid series, those of the indandione series, and those of the isoxazolone series and Z2 represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the naphthothiazole series, those of the naphthoselenazole series, and those of the naphthoxazole series.

6. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of at least 'one cyanine dye selected from those represented by the following general formula wherein R and R1 each represents an alkyl group containing from 1 to 2 carbon atoms, d, m and n each represents a positive integer of from 1 to 2, X represents an acid radical, and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the naphthoselenazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the 2-quinoline series, and those of the 4-quinoline series, and at least one un-ionized dye selected from those represented by the following general formula:

wherein R4 and R5 each represents an alkyl group containing from 1 to 2 carbon atoms, Q represents the nonmetallie atoms necessary to complete a heterocyclic nucleus of the barbituric acid series, and Z2 represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series.

7. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of at least one cyanine dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group containing from 1 to 2 carbon atoms, R3 represents a member selected from the group consistingof a hydrogen atom and an alkyl group containing from l to 2 carbon atoms, X represents an acid radical, n represents a positive integer of from 1 to 2, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the naphthoselenazole series, those of the benzoxazole series, those of the naphthoxazole series, those of the 2-quinoline series and those of the 4-quinoline series, and Z1 represents the non-metallic atoms necessary to complete a heterocyclic nucleus selected from the group consisting of those of the thiazole series, those of the benzothiazole series, those of the naphthothiazole series, those of the benzoselenazole series, those of the naphthoselenazole series, those of the benzoxazole series, and those of the naphthoxazole series, and at least one un-ionized dye selected from those represented by the following general formula:

wherein R, R1, and R3 each represents an alkyl group of the formula CftHzn-H wherein n represents a positive integer of from 1 to 2, X represents an acid radical, and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and at least one un-ionized dye selected from those represented by the following general formula:

wherein R4 and R5 each represents an alkyl group containing from 1 to 2 carbon atoms, Z2 represents the nonmetallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and Q represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the barbituric acid series.

9. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of 9-ethyl- 3,3' dimethyl-4,5,4,5'-dibenzothiacarbocyanine chloride idene)isopropylidenelbarbituric acid.

l0. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of at least one cyanine dye selected from those represented by the following general formula:

wherein R, R1, and R3 each represents an alkyl group of the formula CnII2n+1 wherein n represents a positive integer of from 1 to 2, X represents an acid radical, and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and at least one un-ionized dye selected from those represented by the following general formula:

wherein R4 and R5 each represents an alkyl group containing from l to 2 carbon atoms, Z2 represents the non metallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and Q represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the 2-thiobarbituric acid series.

ll. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of 9-ethyl 3,3dimethyl4, 5, 4,5'-dibenzothiacarbocyanine chloride and 5-[(3-ethy1-2(3H)-a-naphthothiazolylidene) (l ethyl 2( 1H) naphthiazolylidene)isopropylidene]-l-methyl-Z-thiobarbiturie acid.

12. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of at least one cyanine dye selected from those represented by the following general formula:

wherein R and R1 each represents an alkyl group containing from l to 2 carbon atoms, X represents an acid radical, a' represents a positive integer of from l to 2, Z represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzoxazole series, and Zi represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series, and at least one un-ionized dye selected from those represented by the following general formula:

wherein R4 and R5 each represents an alkyl group containing from 1 to 2 carbon atoms, Zz represents the nonmetallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and Q represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the barbituric acid series.

13. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of 3,3di ethyloxathiacarbocyanine iodide and 5-[(1-ethy1-2(1H) naphthothiazolylidene) (l methyl 2( 1H) -naphthothiazolylidene)isopropylidene] 1,3 di( methoxyethyl)barbituric acid.

14. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of at least one cyanine dye selected from those represented by the following general formula:

represented by the following general formula:

//Z\` C=CHC=CH -Rs wherein R4 and R5 each represents an alkyl group containing from l to 2 carbon atoms, Z2 represents the nonmetallic atoms necessary to complete a heterocyclic nucleus of the naphthothiazole series, and Q represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the barbituric acid series.

15. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of 3,3'di ethylselenacyanine iodide 'and 5- l-ethyl-Z 1H) --naphthothiazolylidene) (l methyl 2( 1H) naphthothiazolylidene)isopropylidene] 1,3 di( methoxyethyl)barbituric acid.

16. A photographic gelatino-silver-halide emulsion sensitized with a supersensitizing combination of at least one eyanine dye selected from those represented by the following general formula:

wherein R, R1, and R3 each represents an alkyl group of the formula CnHzn+1 wherein n represents a positive integer of from 1 to 2, X represents an acid radical, and Z and Z1 each represents the non-metallic atoms necessary to complete a heterocyclic nucleus of the benzothiazole series, and at least one un-ionized dye selected from those represented by the following general formula:

No references cited. 

1. A PHOTOGRAPHIC SILVER HALIDE EMULSION SENSITIZED WITH A SUPERSENSITIZING COMBINATION OF AT LEAST ONE CYANINE DYE SELECTED FROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 